Liquid cooling system for internal combustion engine

ABSTRACT

A liquid cooling system for an internal combustion engine includes a coolant pump, an air-to-liquid heat exchanger, and a bypass loop for allowing coolant to circulate from the coolant pump to the engine without passing through the heat exchanger. A thermostatic valve mounted within a thermostat housing and including a temperature-responsive primary valve element and bypass flow control will control the flow of coolant with a spring-loaded valve disc having a conical, annular sealing surface configured for linear contact with the valve seat.

CROSS REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates to a liquid cooling system for a reciprocatinginternal combustion engine.

2. Related Art

Automotive internal combustion engines operate in a variety oftemperature extremes. The first duty of a cooling system is to maintainthe engine's operating temperature within a fairly narrow range. Asexhaust emission control requirements tighten, this function hasincreased in importance.

In addition to controlling the ultimate temperature at which an engineoperates following warm up, the cooling system desirably provides rapidwarm up of the engine so as to provide heat to the passenger cabin of avehicle as quickly as possible. To this end, coolant is circulatedthrough a bypass, which allows the coolant to move through the enginewithout passing through the air-to-liquid heat exchanger, commonlytermed a radiator. Once the engine attains the desired operatingtemperature, flow through the radiator is initiated.

The transition between bypass flow and flow through the radiator must bemanaged carefully so as to avoid undesirable transient flow conditionssuch as valve hammer, a condition characterized by a high frequencyseating and unseating of the valve disc. This has presented a problemwith known thermostatic temperature control devices.

It would be desirable to have a cooling system with a thermostatic valvepermitting finer control of coolant temperature and flow during warm upof the engine, particularly during switchover from bypass to full flowthrough the radiator.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the invention, a liquid cooling system for aninternal combustion engine includes a coolant pump, an air-to-liquidheat exchanger, and a bypass loop for allowing coolant to circulate fromthe coolant pump to the engine without passing through the heatexchanger. A thermostat housing is operatively connected with thecoolant pump, as well as with the heat exchanger and the bypass loop. Athermostatic valve mounted within the thermostat housing includes atemperature-responsive primary valve element for controlling the flow ofcoolant between the coolant pump and the heat exchanger and a bypassflow control coupled to the primary valve element for controlling theflow of coolant through the bypass. The bypass flow control includes aresiliently-loaded valve disc having a conical, annular sealing surfaceconfigured for linear contact with the valve seat.

According to another aspect of the present invention, the valve discfurther includes a number of continuously open bypass orifices formed inthe valve disc. The valve disc is itself mounted upon a stem extendingfrom a temperature-responsive element which operates the primary valveelement.

According to another aspect of the present invention, the thermostaticvalve has at least a first position in which the primary valve elementis closed and the bypass flow control is open to a maximum extent and asecond position in which the primary valve element is open and thebypass flow control is open to a minimum extent.

According to another aspect of the present invention, a bypass flowcontrol includes a valve disc having a conical, annular sealing surfaceconfigured for linear contact with a valve seat incorporated within thethermostat housing. Stated another way, the bypass flow control includesa spring-loaded valve disc with a frustoconical, annular sealing surfaceconfigured for wedging contact with the thermostat housing's valve seat.

It is an advantage of a liquid cooling system according to the presentinvention that transitions between bypass flow, which excludes theengine's radiator, and full flow, which includes the radiator, will bemanaged in a manner so as to avoid unwanted temperature excursions.

It is a further advantage of a liquid cooling system according to thepresent invention that the thermostatic valve will exhibit superiordurability characteristics as compared with prior art valves.

Other advantages, as well as features of the present invention, willbecome apparent to the reader of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a V-block engine having acooling system according to the present invention.

FIG. 2 is a sectional view of a thermostatic valve according to anaspect of the present invention. The valve of FIG. 2 is in the closedposition with respect to flow through the engine's radiator, but withthe bypass flow control being in the open position.

FIG. 3 is similar to FIG. 2, but shows the primary valve element of thethermostatic valve in the open position, allowing flow through theengine's radiator, but with the bypass flow control being in a closedposition, in which only liquid flowing through the bypass flows througha series of orifices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, engine 10 has a cylinder block, 11, upon which apair of cylinder heads, 12, are mounted, with only one of cylinder heads12 being shown. Engine 10 also includes a coolant pump, 14, a coolantcrossover, 16, an air-to-liquid heat exchanger (“radiator”) 18, and aseries of hoses. Coolant circulates generally from water pump 14 throughcylinder block 11 and up through cylinder heads 12. After moving throughcylinder heads 12, coolant flows into thermostat housing 26 which, asits name implies, provides a mounting place for thermostatic valve 34,including a bypass valve seat, 72 (FIGS. 2 and 3). When thermostaticvalve 34 is in the open position shown in FIG. 3, coolant flows upthrough thermostatic valve 34 and then through coolant outlet 30 andupper radiator hose 20, and then into radiator 18. The cooled fluid thenmoves through lower radiator hose 24 and then through water pump 14.Leaving water pump 14, the fluid flows back through cylinder block 11,as described above.

When engine 10 is below the desired operating temperature,thermostatically responsive valve 34 will not allow coolant to flowthrough radiator hose 20 and into radiator 18. Rather, coolant flowsthrough a bypass loop, 22, which is shown as including a passageway toand from water pump 14 and through cylinder heads 12 and cylinder block11, but without including flow through radiator 18. This bypass flowallows engine 10 to warm up more rapidly. The lower temperaturecondition of valve 34 is shown in FIG. 2, wherein valve 34 is closedinsofar as flow to radiator 18 is concerned. Thus, in FIG. 2, primaryvalve 46 is maintained in contact with valve cage 50 by means of primaryspring 54. Note that FIG. 2 also shows resiliently-loaded bypass valvedisc 58, which is slidingly mounted upon stem 52, as being in a fullyopen position. This allows maximum flow through bypass loop 22.

Primary valve element 38 has a temperature-responsive motor in the formof wax pellet motor 42, which has a plunger 44. When engine 10 is cold,wax pellet motor 42 is in a retracted position, allowing primary valveelement 46 to shut off flow to radiator 18. Once engine 10 comes to awarmed up operating temperature, however, notice from FIG. 3 thatplunger 44 now extends from wax pellet motor 42, with the result thatprimary valve element 46 has now been displaced from valve cage 50,thereby allowing flow through water outlet 30 and through upper radiatorhose 20 to radiator 18.

Returning now to FIG. 2, it is seen that frustoconical, annular sealingsurface 64 of valve disc 58 is not in contact with valve seat 72,thereby allowing bypass flow through bypass loop 22 and, therefore,rapid warm up of engine 10. Now, however, turning once again to FIG. 3,it is seen that with the action of wax pellet motor 42 and,particularly, plunger 44, bypass valve disc 58 has now been resilientlypressed into contact with valve seat 72, such that the force of spring62 maintains frustoconical sealing surface 64 in contact with valve seat72.

When thermostatic valve element 34 is in the position shown in FIG. 3,minimal flow is allowed through bypass orifices 68 which are formed inbypass valve disc 58. Orifices 68 are important because they wouldpermit minimum flow through engine 10 even if thermostatic valve element34 were to malfunction and not open correctly. Orifices 68 also help toprovide a “soft” temperature transition strategy by preventing valvedisc 58 from closing too quickly. Moreover, frustoconical sealingsurface 64 helps to prevent valve disc 58 from closing in an unstablemanner by mitigating the pressure forces acting upon valve disc 58. Inturn, this enhances the durability of thermostatic valve element 34.

It is thus seen that wax pellet motor 42 functions as a thermallyresponsive linear actuator which positions bypass valve disc 58 againstseat 72. As noted above, when thermostatic valve element 34 is in theposition shown in FIG. 3, bypass valve disc 58 is maintained in contactwith seat 72 by bypass spring 62, which functions as a resilient member.

Although thermostatic valve element 34 is illustrated as having a firstposition in which primary valve element 46 is closed and bypass flowcontrol disc 58 is open, and a second position in which primary valveelement 46 is open and bypass flow control disc 58 is open to a minimumextent while closed against seat 72, other types of thermostatic controldevices may employ the present temperature-responsive primary valveelement and bypass valve disc in multiple locations or operationalconfigurations.

The foregoing invention has been described in accordance with therelevant legal standards, thus the description is exemplary rather thanlimiting in nature. Variations and modifications to the disclosedembodiment may become apparent to those skilled in the art and fallwithin the scope of the invention. Accordingly the scope of legalprotection afforded this invention can only be determined by studyingthe following claims.

1. A liquid cooling system for an internal combustion engine, comprising: a coolant pump; an air-to-liquid heat exchanger; a bypass loop for allowing coolant to circulate from the coolant pump to the engine without passing through the heat exchanger; a thermostat housing operatively connected with said coolant pump, as well as with said heat exchanger and said bypass loop; and a thermostatic valve mounted within said thermostat housing, with said thermostatic valve comprising: a temperature-responsive primary valve element for controlling a flow of coolant between said coolant pump and said heat exchanger; and a bypass flow control, coupled to said primary valve element, for controlling a flow of coolant through said bypass, with said bypass flow control comprising a resiliently biased valve disc having a conical, annular sealing surface configured for linear contact with a valve seat.
 2. A liquid cooling system according to claim 1, wherein said valve disc further comprises a plurality of continuously open bypass orifices formed in said valve disc.
 3. A liquid cooling system according to claim 1, wherein said valve disc is mounted upon a stem extending from a temperature-responsive element which operates said primary valve element.
 4. A liquid cooling system according to claim 1, wherein said valve seat is incorporated within said thermostat housing.
 5. A liquid cooling system according to claim 1, wherein said thermostatic valve has at least a first position in which said primary valve element is closed and said bypass flow control is open to a maximum extent, and a second position in which said primary valve element is open and said bypass flow control is open to a minimum extent.
 6. A liquid cooling system according to claim 1, wherein said valve disc is spring loaded.
 7. A thermostatic valve for use within a cooling system of a liquid cooled internal combustion engine, comprising: a temperature-responsive primary valve element for controlling a flow of coolant between a coolant pump and a heat exchanger; and a bypass flow control, coupled to said primary valve element, for controlling a flow of coolant through a warm up bypass, with said bypass flow control comprising a valve disc having a conical, annular sealing surface configured for linear contact with a valve seat.
 8. A thermostatic valve according to claim 7, wherein said primary valve element is positioned normally closed by a resilient member and opened by a thermally responsive linear actuator.
 9. A thermostatic valve according to claim 7, wherein said valve disc is configured to permit a partial flow past the disc when the disc is in contact with a valve seat.
 10. A thermostatic valve for use within a cooling system of a liquid cooled internal combustion engine, comprising: a temperature-responsive, linearly actuated primary poppet valve for controlling a flow of coolant between a coolant pump and a heat exchanger; and a bypass flow control, resiliently coupled to said poppet valve, for controlling a flow of coolant through a warm up bypass, with said bypass flow control comprising a resiliently-loaded valve disc having a frustoconical, annular sealing surface configured for wedging linear contact with a valve seat.
 11. A thermostatic valve according to claim 10, wherein said resiliently-loaded valve disc is configured for contact with a valve seat incorporated within a thermostat housing.
 12. A thermostatic valve according to claim 10, wherein said resiliently-loaded valve disc is spring-loaded. 